The present invention relates to a voltage regulation system for a charging generator, or more in particular, to a voltage regulation system for a charging generator of digital IC type suitable for use on automobiles.
In a conventional voltage regulation system for an automotive charging generator, the output voltage of a generator is divided and compared with a reference voltage to control the on-off operation of a power element.
Also, the specification of U.S. Pat. No. 4,385,270 discloses a system for regulating an output voltage in which a triangular wave of a predetermined frequency is utilized as a reference voltage to control the on-off frequency of a power element.
In the above-mentioned prior art systems, although the on-off frequency of the power element is constant, the on-off switching timing thereof is determined by a field current that changes with an external load or the like. Accordingly, the on-off operation of the power element is accompanied by a sudden change in output voltage and causes a surge voltage, thus inducing such a problem as radio noises.
In recent years, however, with the increase in the electrical load including the power steering system and the like, the output level requirement of the automotive charging generator has been increased. On the other hand, with the improvement in the sensitivity of car radio receivers, etc., more and more attention has been directed to the problem of radio noises of radio receivers operating in medium wave region.